I have many mulit select attributes and this not saved any valus , What I can do ?
Can you please specify your problem in detail? How you save the data in system or etc.
@magento2
I Found Solution after R&D On Magento database.
Login In your phpmyadmin
Go to your website database
Open "eav_attribute" table
Find Your multiselect "attribute_id"
Edit Row
If "backend_model" Column blank then paste this
Magento\Eav\Model\Entity\Attribute\Backend\ArrayBackend
and Please see this
https://magento.stackexchange.com/questions/224621/warning-array-filter-expects-parameter-1-to-be-ar...
That column has already that value!
In my case it was just cleaning cache and reindexing.
sudo php bin/magento c:c sudo php bin/magento c:f sudo php bin/magento i:reind